Flow cytometry is an important tool for research and clinical applications. Historically, the technique has advanced with the introduction of new measurement parameters. The goal of this project is to develop and evaluate two new techniques for flow cytometry, based on use of the two-frequency, Zeeman effect laser. The two techniques, Zeeman Interferometry and Phase Differential Scattering, are experimentally similar, but give very different information. Zeeman Interferometry can be used to measure the net optical pathlength of a particle. This is related to the particle's dry mass. Phase Differential Scattering gives information about the size, morphology, internal structure, and optical activity of the scattering particle. The information obtained is different from that given by conventional light scattering methods. The usefulness of Zeeman Interferometry and Phase Differential Scattering, when used in conjunction with conventional flow cytometric parameters, will be investigated for different biological applications including karyotype analysis, 1 cell-cycle studies, and discrimination between biological cells.